Background: Primary cadaveric studies were reviewed to give a contemporary overview of what is known about innervation of the female breast and nipple/nipple-areola complex. Methods: The authors performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses–compliant systematic review and meta-analysis. The authors searched four electronic databases for studies investigating which nerve branches supply the female breast and nipple/nipple-areola complex or describing the trajectory and other anatomical features of these nerves. Inclusion criteria for meta-analysis were at least five studies of known sample size and with numerical observed values. Pooled prevalence estimates of nerve branches supplying the nipple/nipple-areola complex were calculated using random-effects meta-analyses; the remaining results were structured using qualitative synthesis. Risk of bias within individual studies was assessed with the Anatomical Quality Assurance checklist. Results: Of 3653 studies identified, 19 were eligible for qualitative synthesis and seven for meta-analysis. The breast skin is innervated by anterior cutaneous branches and lateral cutaneous branches of the second through sixth and the nipple/nipple-areola complex primarily by anterior cutaneous branches and lateral cutaneous branches of the third through fifth intercostal nerves. The anterior cutaneous branch and lateral cutaneous branch of the fourth intercostal nerve supply the largest surface area of the breast skin and nipple/nipple-areola complex. The lateral cutaneous branch of the fourth intercostal nerve is the most consistent contributory nerve to the nipple/nipple-areola complex (pooled prevalence, 89.0 percent; 95 percent CI, 0.80 to 0.94). Conclusions: The anterior cutaneous branch and lateral cutaneous branch of the fourth intercostal nerve are the most important nerves to spare or repair during reconstructive and cosmetic breast surgery. Future studies are required to elicit the course of dominant nerves through the breast tissue.

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AIMS The aims of this review were (i) to evaluate whether patient-reported outcome measures used in clinical studies for assessing sensation after mastectomy and breast reconstruction are suitable for this purpose, and (ii) to explore whether any measures used for assessing sensation after non-oncologic breast surgery are worth modifying for use in post-mastectomy patients. Methods PRISMA guidelines were followed (PROSPERO number CRD42020178066). We searched six databases for studies of oncologic (i.e., therapeutic, prophylactic, and reconstructive) and non-oncologic breast surgery (e.g., breast reduction) in which sensation was assessed with a patient-reported outcome measure. From the selected studies, we extracted eligible measures, evaluated their fitness for purpose, and summarized the content of sensation-specific items. Results Of 6728 articles identified, we selected 135 studies that used 124 eligible patient-reported outcome measures. For 97% of these measures, details regarding development and measurement properties were unavailable. Four (3%) validated measures-the Sensory Disturbances subscale of the Breast Cancer Sequelae Cause Scales, the Discomfort subscale of the Breast Sensation Assessment Scale (BSAS), Didier et al.'s questionnaire for "Assessment of the patients' satisfaction with cosmetic results, physical and emotional impact of mastectomy", and the Breast Specific Pain subscale of the Breast Cancer Treatment Outcomes Scale (BCTOS)-each contain at least one item pertaining to breast sensation, but target different concepts of interest. In total, the measures feature 215 sensation-specific items, most of which concern symptom severity (97%) as opposed to impact on daily functioning (3%). Conclusion Patient-reported outcome measures used in clinical studies for assessing sensation after mastectomy and breast reconstruction are unsuitable for this purpose: they are either non-validated or non-specific. We failed to identify any measures for use in non-oncologic breast surgery populations worth modifying. To collect meaningful, patient-relevant data regarding sensation after mastectomy, it is pertinent that future clinical trials adopt psychometrically robust, specific patient-reported outcome measures. Hansje P. Smeele and Rachel C. H. Dijkstra have made an equal contribution to the work.

Background The aims of this study were to assess whether sensory nerve coaptation in free flap breast reconstruction is subject to learning, and to elucidate challenges of this technique. Methods In this single-center retrospective cohort study, we reviewed consecutive free flap breast reconstructions performed between March 2015 and August 2018. Data were extracted from medical records, and missing values imputed. We assessed learning by exploring associations between case number and probability of successful nerve coaptation using a multivariable mixed-effects model. Sensitivity analysis was performed in a subgroup of cases with evidence of attempted coaptation. Recorded reasons for failed coaptation attempts were grouped into thematic categories. Multivariable mixed-effects models were used to examine associations between case number and postoperative mechanical detection threshold. Results Nerve coaptation was completed in 250 of 564 (44%) included breast reconstructions. Success rates varied considerably between surgeons (range 21-78%). In the total sample, the adjusted odds of successful nerve coaptation increased 1.03-fold for every unit increase in case number (95% confidence interval 1.01 – 1.05, p < .05), but sensitivity analysis refuted this apparent learning effect (adjusted odds ratio 1.00, 95% confidence interval 1.00 – 1.01, p = .34). The most frequently recorded reasons for failed nerve coaptation attempts were inability to locate a donor or recipient nerve. Postoperative mechanical detection thresholds showed a negligible, positive association with case number (estimate 0.00, 95% confidence interval 0.00 – 0.01, p < .05). Conclusions This study does not provide evidence in support of a learning process for nerve coaptation in free flap breast reconstruction. Nevertheless, the identified technical challenges suggest that surgeons may benefit from training visual search skills, familiarizing with relevant anatomy, and practicing techniques for achieving tensionless coaptation. This study complements prior studies exploring therapeutic benefit of nerve coaptation by addressing technical feasibility.